Oil and gas wells produce oil, gas and/or petroleum byproducts from subterranean hydrocarbon reservoirs. Various methods and systems are utilized to drill wells into such a reservoir and then extract hydrocarbons from the drilled wells. To enhance hydrocarbon production from the reservoir, stimulation treatments are typically applied to improve near wellbore permeability/conductivity in the subterranean reservoir formation. One example of a commonly used stimulation treatment is the acid treatment, in which an acid based fluid mixture is injected into the subterranean reservoir formation to stimulate and increase the production of hydrocarbons from the reservoir. This is commonly referred to as acidizing. One such aqueous acid treatment, referred to as “matrix-acidizing”, involves the introduction of an acid into a subterranean reservoir formation under a pressure below the formation fracture pressure so that the acid flows through the pore spaces of the reservoir formation. The acid of the aqueous acid treatment reacts with acid soluble materials contained in the reservoir formation to increase the size of the pore spaces and increase the permeability of the reservoir formation.
Wellbores are often drilled through reservoir formations that include two or more production zones. Such wells are typically completed by placing a casing along the wellbore length and perforating the casing adjacent each such production zone to extract the formation fluids (such as hydrocarbons) into the wellbore. These production zones are sometimes separated from each other by installing a packer between the production zones. During fluid injection, the fluid penetrates these zones. The extent of fluid penetration in each zone depends on the permeability and the reservoir pressures.
Due to heterogeneities in permeability and pressures in the formations surrounding the wellbore, sometimes the fluids flow from one zone into the wellbore and out into another zone. This phenomenon is called wellbore crossflow and is observed in commingled reservoirs. The crossflow can, for example, lead to inadequate fluid placement during scale-squeeze treatments, as well as to partial stimulation of high pressure zones during matrix acidizing. Real-time wellbore temperature measurements are commonly used to monitor fluid distribution during an injection treatment. However, crossflow effects are generally unnoticeable using temperature measurements acquired at high injection rates, as wellbore temperatures are dominated by a high temperature of an injected fluid, and therefore, produced fluids related to crossflow are unable to affect the wellbore temperatures significantly.